Comparison of Apparent Depth in a Photograph Viewed from Two Distances
Olin W. Smith · Perceptual and Motor Skills · 1958
In a previous experiment S's monocular field of view was restricted to the image area of a photograph of a tridimensional scene (3). When the separation of S's eye and the photograph increased or decreased, Ss reported that the depth of the scene appeared to lengthen and shorten. The only feature of the scene which appeared to change was its depth. The present experiment was undertaken in order to verify this phenomenon. Preliminary observations confirmed Schlosberg's findings that compelling impressions of depth may be induced by photographs of tridimensional scenes (2). When a photograph of a corridor was viewed as above, Ss could easily imagine how many paces they would have to take in order to walk from where they were located to specified points in rhe space portrayed by the picture. Consequently, differences in estimated paces to points within the scene were taken as an operational index of depth impressions when the photograph was viewed from two distances. METHOD Apparatw and procedwe.-A 36 X 45-in. photomural of a corridor 360 ft. long was made from a 4 X 5-in. achromatic negative exposed through a 5-in. Ekrar lens. The camera had been mounted 5% fc. above the floor, and equidistant from the side walls of one end of the corridor. The photomural was mounted on heavy illustration board by the dry press method and enclosed in a plywood frame. A pair of tracks carried a dolly on which was mounted the photomural and 2 cool-light 40-w fluorescent tubes. These were adjusted so that the photograph at either distance appeared to be uniformly illuminated. E moved the dolly back and forth by means of a handcrank. The 2 viewing distances of 2 ft. and 91/2 ft. subtended horizontal visual angles of 23 and 86 at S's eye, respectively. A monocular viewing apparatus held interchangeable slides in a black box, which restricted S's field of view ro the image area of the print at each viewing distance. All equipment was screened from S except for the eyepiece and adjustable stool on which S sat while observing. Ss were 52 paid Cornell srudents. S's rask was to estimate how many paces he would need to walk: (a) from where he was to a nearby point in the scene, and (b) from this nearby point to the end of the corridor. Both estimates were made twice for both viewing distances of the photograph. The serial order of the distance settings of the photograph was 2, 91/2,2, and 9% ft., This research was supported in part by Contract AF18-(600-443) between Cornell University and the USAF, HmL, ARDC, Bolling AFB, Washington, D. C. Permission is granted to the U. S. Govt. to reproduce the text in whole or in part.